1. Field
This various circuit embodiments described herein relate in general to improvements in hard disk drive write systems, and, more specifically, to improvements in systems, methods, and apparatuses for shifting a duty cycle of a write signal in hard disk drive write systems.
2. Background
Hard disk drives are mass storage devices that include a magnetic storage media, such as rotating disks, platters, or the like, a channel chip, a preamp chip, one or more positionable write heads, an interconnect between the channel and preamp chips, and an interconnect between the preamp chip and write head. The conventional write heads comprise magneto-resistive heads adapted to write data to the magnetic storage media when current is passed through them. The signal path for the writing process in a hard disk drive system includes all of these components.
When data is written to the disk, electrical current pulses are applied to the write heads according to coding rules to produce a magnet flux change in the write heads that is applied to the magnetic storage medium. However, the transition between a positive write data pulse and a negative write data pulse can systematically shift in either direction due to any of the components in the signal path, especially in the channel chip and the long interconnect between the channel and preamp chips.
What is needed is a mechanism to compensate for this systematic shift in the transition between positive and negative write data pulses. This compensation can be considered to be a duty cycle shift for the write data.